U.S. patent application number 11/521405 was filed with the patent office on 2007-05-24 for method of driving high definition opposed discharge plasma display panel.
This patent application is currently assigned to MARKETECH INTERNATIONAL CORP.. Invention is credited to Sheng-Wen Hsu, Hsu-Chia Kao, Hsu-Pin Kao, Jang-Jeng Liang, Tsan-Hung Tsai.
Application Number | 20070115212 11/521405 |
Document ID | / |
Family ID | 38052981 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070115212 |
Kind Code |
A1 |
Kao; Hsu-Pin ; et
al. |
May 24, 2007 |
Method of driving high definition opposed discharge plasma display
panel
Abstract
The present invention is to provide a method of driving a high
definition opposed discharge PDP comprising transversely disposing
a barrier rib on a center of any elongate discharge cells of the
opposed discharge PDP to divide the discharge cell into two
sub-cells; disposing a sustain electrode on a front substrate
corresponding to either sub-cell; causing a driving circuit to
apply a sustaining pulse to each of the plurality of sustain
electrodes in a sustaining period of each sub-field; and causing a
phase of the sustaining pulse on the sustain electrode
corresponding to one sub-cell to have a phase difference of 180
degrees relative to that of the sustaining pulse on the sustain
electrode corresponding to the other adjacent sub-cell in order to
effectively eliminate noise caused by vibration of the opposed
discharge PDP in discharge, reducing peak current and
electromagnetic interference, and greatly increase both light
emitting efficiency and brightness of the opposed discharge
PDP.
Inventors: |
Kao; Hsu-Pin; (Pingjhen
City, TW) ; Liang; Jang-Jeng; (Taoyuan City, TW)
; Tsai; Tsan-Hung; (Sanchong City, TW) ; Hsu;
Sheng-Wen; (Taipei City, TW) ; Kao; Hsu-Chia;
(Pingjhen City, TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
US
|
Assignee: |
MARKETECH INTERNATIONAL
CORP.
Taipei
TW
|
Family ID: |
38052981 |
Appl. No.: |
11/521405 |
Filed: |
September 15, 2006 |
Current U.S.
Class: |
345/60 |
Current CPC
Class: |
G09G 2330/025 20130101;
G09G 3/297 20130101; G09G 2330/06 20130101 |
Class at
Publication: |
345/060 |
International
Class: |
G09G 3/28 20060101
G09G003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2005 |
TW |
094140919 |
Claims
1. A method of driving a high definition opposed discharge plasma
display panel (PDP) comprising: transversely disposing a barrier
rib on a center of any one of a plurality of elongate discharge
cells in any one of a plurality of pixels of the opposed discharge
PDP wherein the discharge cell is divided into two sub-cells by the
barrier rib; disposing a sustain electrode on a front substrate
corresponding to either sub-cell; causing a driving circuit to
apply a sustaining pulse to each of the plurality of sustain
electrodes in a sustaining period of each sub-field; and causing a
phase of the sustaining pulse on the sustain electrode
corresponding to one sub-cell to have a phase difference of 180
degrees relative to that of the sustaining pulse on the sustain
electrode corresponding to the other adjacent sub-cell.
2. A method of driving a high definition opposed discharge plasma
display panel (PDP) comprising: transversely disposing a barrier
rib on a center of any one of a plurality of elongate discharge
cells in any one of a plurality of pixels of the opposed discharge
PDP wherein the discharge cell is divided into two sub-cells by the
barrier rib; disposing a sustain electrode on a front substrate
corresponding to either sub-cell; causing a driving circuit to
apply a sustaining pulse to each of the plurality of sustain
electrodes in a sustaining period of each sub-field; and causing a
phase of the sustaining pulse on the sustain electrode
corresponding to one sub-cell to have a phase difference of 180
degrees relative to that of the sustaining pulse on the sustain
electrode corresponding to the other spaced sub-cell.
3. The method of claim 2, further comprising causing a phase of the
sustaining pulse on the sustain electrode corresponding to one
sub-cell of the discharge cell to be equal to that of the
sustaining pulse on the sustain electrode corresponding to the
other adjacent sub-cell of the same discharge cell.
4. The method of claim 2, further comprising causing the sustaining
pulse on the sustain electrode corresponding to the other sub-cell
of the same discharge cell to have a zero potential.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to opposed discharge plasma
display panels (PDPs), and more particularly to a method of driving
a high definition opposed discharge PDP in order to effectively
eliminate noise caused by vibration of the opposed discharge PDP in
discharge and greatly increase both light emitting efficiency and
brightness of the opposed discharge PDP.
BACKGROUND OF THE INVENTION
[0002] A method of manufacturing a conventional opposed alternating
current discharge (i.e., AC type) PDP 10 is illustrated in FIG. 1,
wherein two different layers are formed on two opposed glass
substrates 11 and 12, the peripheries of the glass substrates 11
and 12 are sealed together to form a space between the two glass
substrates, specific gas (e.g., helium (He), neon (Ne), xenon (Xe),
or argon (Ar)) is mixed in a predetermined ratio and is filled in
discharge cells 13 formed within the space between the two glass
substrates 11 and 12. The substrate facing a viewer is defined as a
front substrate 11 in the PDP as shown in FIG. 1. On the inner side
of the front substrate 11, there are sequentially provided with a
plurality of parallel transparent electrodes 111, a plurality of
bus electrodes 112, a dielectric layer 113, and a protection layer
(e.g., MgO) 114. On the inner side of the opposed rear substrate
12, there are sequentially provided with a plurality of parallel
data electrodes 121, a dielectric layer 124, a plurality of barrier
ribs 122, and phosphor 123 uniformly coated on each of the barrier
ribs 122 in which the phosphor 123 can be a red, green, or blue
phosphor. In response to applying voltage to the positions of
electrodes 111, 112, and 121, the corresponding dielectric layers
113 and 124 discharge in the discharge cell 13 formed between the
adjacent barrier ribs 122, enabling the phosphor 123 in the
discharge cell 13 to emit light with a corresponding color.
[0003] Referring to FIG. 2, in the conventional AC type PDP 10, the
electrodes 111 and 112 are typically made by utilizing sputtering
and photolithography or printing techniques to form a plurality of
spaced, parallel transparent electrodes 111 on the inner side of
the front substrate 11, and then utilizing sputtering (or vaporing)
and photolithography techniques to form a plurality of bus
electrodes 112 on the transparent electrodes 111 in order to
decrease line impedance of the transparent electrodes 111 by
utilizing the bus electrodes 112. The transparent electrodes 111
(comprising the bus electrodes 112) and the corresponding data
electrodes 121 on the rear substrate 12 together form two opposed
electrodes. In response to applying voltage to the electrodes 111
and 121, the dielectric layers 113 and 124 perform opposed
discharges in the corresponding discharge cell 13. As a result, the
mixed gas filled in the discharge cell 13 discharges to emit
ultraviolet (UV). And in turn, red, green, and blue light is
emitted by the phosphor 123 coated on the discharge cell 13. As a
result, an image is shown. The conventional AC type PDP 10 is also
called as opposed discharge PDP.
[0004] Referring to FIGS. 1, 2, and 3, in the above opposed
discharge PDP 10 the parallel data electrodes 121 of the rear
substrate 12 are provided on bottom of the dielectric layer 124 and
are disposed perpendicularly to the corresponding transparent
electrodes (also called as scan electrodes or sustain electrodes)
111 of the front substrate 11 at the positions corresponding to the
discharge cells 13. A shadow mask 20 is formed on top of the
dielectric layer 124. A plurality of shadow holes 21 of the shadow
mask 20 are employed as space for the discharge cell 13. Also,
metal conductor around each shadow hole 21 is served as barrier rib
122 around the discharge cell 13.
[0005] Referring to FIGS. 1 to 3 again, in the above opposed
discharge PDP 10 portion of a shadow mask 20 of a 34'' opposed
discharge PDP 10 having Video Graphics Adapter (VGA) resolution is
shown. Each pixel containing three discharge cells for emitting
red, green, and blue light respectively has a size of 1080
.mu.m.times.1080 .mu.m. That is, each discharge cell has a size of
360 .mu.m.times.1080 .mu.m. Referring to FIG. 4, a driving scheme
is created by a driving circuit of the PDP 10 for showing each
sub-field. The driving scheme comprises three driving sequences,
i.e., a first addressing sequence, a second sustaining sequence,
and a third erasing sequence wherein, in the addressing sequence,
the driving circuit applies a negative voltage pulse to each bus
electrode 112. At the same time, the driving circuit applies a
positive data pulse to the address electrode 121 based on an image
to be displayed. At this time, due to the shadow mask 20 is made by
the conductive metal material, electric field in the discharge cell
13 becomes non-uniform, i.e. the electric field adjacent to the
wall of the shadow hole 21 (i.e., barrier rib 122) is relatively
strong and the electric field at a center of the shadow hole 21 is
relatively weak. Discharge first occurs at wall of the shadow hole
21 when an addressing pulse is applied to the discharge cell 13,
which enables the charged particles in the discharge cell 13
quickly spread and propagate toward the center of the shadow hole
21 so as to induce an opposed discharge between the bus electrodes
112 and the data electrodes 121. The opposed discharge scheme not
only greatly increases light emitting efficiency of the PDP 10 but
also obtains advantages such as high contrast, high writing speed,
and low cost.
[0006] Referring to FIGS. 1 and 2 again, in the above opposed
discharge PDP 10 however, the barrier rib 122 of the rear substrate
12 is formed of metal conductor around each shadow hole 21 of the
shadow mask 20. Noise generated by the metal barrier rib 122 is far
more serious than that generated by a barrier rib formed of the
well known glass substrate when discharge occurs in the discharge
cell 13. Referring to FIG. 4 again, for the above opposed discharge
PDP 10 in the sustaining period a phase of the sustaining pulse of
the nth sustain electrode is the same as that of the sustaining
pulse of the n+1.sup.th sustain electrode. That is, phase of the
odd number pixels and that of the even number pixels are the same
with respect to voltage shape in the sustaining sequence. Thus,
vibration direction of noise generated by the discharge cells 13 in
the discharge is the same. As a result, noise is significantly
serious. Therefore, if an intimate contact between an inner surface
of the front substrate 11 and the shadow mask 20 is not made in the
process of manufacturing, gap formed therebetween will further
deteriorate the noise problem caused in the opposed discharge PDP
10. Thus, it is desirable to strictly control flatness of the front
and rear substrates 11 and 12 and the shadow mask 20 in order to
decrease the gap created due to an irrregularity between the front
substrate 11 and the shadow mask 20 in the manufacturing process.
The decreased gap can effectively decrease the noise problem.
However, such strict control results in a great increase of process
difficulty and a decreased yield.
[0007] Referring to FIGS. 1, 2 and 5, moreover in the above opposed
discharge PDP 10 portion of a shadow mask 20 of a 34'' opposed
discharge PDP 10 having VGA resolution is shown. Since each pixel
contains three discharge cells for emitting red, green, and blue
light respectively, each discharge cell corresponding to each
shadow hole 21 of the shadow mask 20 has a size of 360
.mu.m.times.1080 .mu.m and is elongate. Such elongate discharge
cells 13 may cause discharge to concentrate on a center thereof.
This can greatly decrease light emitting efficiency of phosphor
coated on distal ends relative to the center of the discharge cell
13. As a result, the total light emitting efficiency is very low.
Thus, a need for improvement exists.
SUMMARY OF THE INVENTION
[0008] After considerable research and experimentation, a method of
driving a high definition opposed discharge plasma display panel
(PDP) according to the present invention has been devised so as to
overcome the above drawbacks (e.g., noise and low light emitting
efficiency) of the prior art.
[0009] It is an object of the present invention to provide a method
of driving a high definition opposed discharge PDP comprising
transversely disposing a barrier rib on a center of any one of a
plurality of elongate discharge cells in any one of a plurality of
pixels of the opposed discharge PDP wherein the discharge cell is
divided into two sub-cells by the barrier rib; disposing a sustain
electrode on a front substrate corresponding to either sub-cell;
causing a driving circuit to apply a sustaining pulse to each of
the plurality of sustain electrodes in a sustaining period of each
sub-field; and causing a phase of the sustaining pulse on the
sustain electrode corresponding to one sub-cell to have a phase
difference of 180 degrees relative to that of the sustaining pulse
on the sustain electrode corresponding to the other adjacent
sub-cell. By utilizing this method, discharge direction of the
sub-cell corresponding to odd number pixel is opposite to that of
the sub-cell corresponding to even number pixel in order to
effectively eliminate noise caused by vibration of the opposed
discharge PDP in discharge. Moreover, a reduction of peak current
and electromagnetic interference is made possible. In addition,
area coated with phosphor is significantly increased because the
discharge cell is divided into two sub-cells. As a result, both
light emitting efficiency and brightness of the opposed discharge
PDP are greatly increased, and thus image with high quality is
shown.
[0010] One aspect of the present invention the method comprises
causing a driving circuit to apply a sustaining pulse to each of
the plurality of sustain electrodes; and causing a phase of the
sustaining pulse on the sustain electrode corresponding to one
sub-cell to have a phase difference of 180 degrees relative to that
of the sustaining pulse on the sustain electrode corresponding to
the other adjacent sub-cell. By utilizing this method, discharge
directions of two adjacent sub-cells of the discharge cell are
opposite in order to substantially eliminate noise caused by
vibration of the opposed discharge PDP in discharge due to opposite
vibration directions.
[0011] Another aspect of the present invention the method comprises
lighting spaced sub-cells; and causing a waveform of a voltage
pulse of one sub-cell is delayed half period (i.e., phase
difference of 180 degrees) relative to that of the other spaced
sub-cell in a sustaining period in order to let discharge
directions of two spaced sub-cells to be opposite with each other.
By utilizing this method, the brightness of the opposed discharge
PDP decreases to about half of that when both sub-cells are lit. As
a result, an overall brightness of the opposed discharge PDP is
decreased in order to adjust the brightness of each gray-scale for
decreasing a minimum brightness and obtaining a fine image in low
gray-scales of the opposed discharge PDP.
[0012] The above and other objects, features and advantages of the
present invention will become apparent from the following detailed
description taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a sectional view of a conventional opposed
discharge PDP;
[0014] FIG. 2 is an exploded perspective view of the PDP of FIG. 1
showing its front and rear substrates;
[0015] FIG. 3 is a sectional view showing a configuration of the
discharge cells, the bus electrodes, and the barrier rib in the PDP
of FIG. 1;
[0016] FIG. 4 is a graph of a driving scheme created by a driving
circuit of the PDP of FIG. 1 for showing each sub-field;
[0017] FIG. 5 is a photograph of an enlarged pixel of the PDP of
FIG. 1;
[0018] FIG. 6 is a sectional view showing a configuration of
discharge cells according to opposed discharge PDP of a first
preferred embodiment of the invention;
[0019] FIG. 7 is a sectional view showing a configuration the
discharge cells, the barrier ribs, and the electrode lines in the
PDP of FIG. 6;
[0020] FIG. 8 is a graph of a driving scheme created by a driving
circuit of the PDP of FIG. 6 for showing each sub-field;
[0021] FIG. 9 schematically depicts an opposed discharge between
two adjacent sub-cells in discharge where the sub-cells correspond
to odd number and even number pixels of the PDP of FIG. 6
respectively;
[0022] FIG. 10 is a sectional view showing a configuration of the
discharge cells, the barrier ribs, and the electrode lines
according to opposed discharge PDP of a second preferred embodiment
of the invention;
[0023] FIG. 11 is a graph of a driving scheme created by a driving
circuit of the PDP of FIG. 10 for showing each sub-field;
[0024] FIG. 12 schematically depicts an opposed discharge between
two adjacent sub-cells in discharge where the sub-cells correspond
to odd number and even number pixels of the PDP of FIG. 10
respectively;
[0025] FIG. 13 is a graph of a driving scheme created by a driving
circuit of opposed discharge PDP according to a third preferred
embodiment of the invention for showing each even number
sub-field;
[0026] FIG. 14 schematically depicts an opposed discharge between
two adjacent sub-cells in discharge where the sub-cells correspond
to odd number and even number pixels of the PDP of FIG. 13
respectively;
[0027] FIG. 15 is a graph of a driving scheme created by a driving
circuit according to the PDP of FIG. 13 for showing each odd number
sub-field; and
[0028] FIG. 16 schematically depicts an opposed discharge between
two adjacent sub-cells in discharge where the sub-cells correspond
to odd number and even number pixels of the PDP of FIG. 15
respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] The invention is directed to a method of driving a high
definition opposed discharge plasma display panel (PDP) comprising
transversely disposing a barrier rib on a center of any elongate
discharge cell in any pixel of the opposed discharge PDP wherein
the discharge cell is divided into two sub-cells by the barrier
rib; disposing a sustain electrode on a front substrate
corresponding to either sub-cell; causing a driving circuit to
apply a sustaining pulse to each of the plurality of sustain
electrodes in a sustaining period of each sub-field; and causing a
phase of the sustaining pulse on the sustain electrode
corresponding to one sub-cell to have a phase difference of 180
degrees relative to that of the sustaining pulse on the sustain
electrode corresponding to the other adjacent sub-cell such that
two adjacent sub-cells may discharge in opposite directions.
Alternatively, the method comprises causing a phase of the
sustaining pulse on the sustain electrode corresponding to one
sub-cell to have a phase difference of 180 degrees relative to that
of the sustaining pulse on the sustain electrode corresponding to
the other spaced sub-cell such that two spaced sub-cells may
discharge in opposite directions.
[0030] Referring to FIG. 6, a first preferred embodiment of the
invention is illustrated with respect to a 34'' opposed discharge
PDP. Each pixel on the opposed discharge PDP has a size of 1080
.mu.m.times.1080 .mu.m. A transverse barrier rib 323 is provided on
a center of any elongate discharge cell 33 in any pixel so as to
divide the discharge cell 33 into two sub-cells 331 and 332. That
is, n.sup.th row discharge cell is divided into n.sup.th-a row
sub-cell 331 and n.sup.th-b row sub-cell 332. Either sub-cell 331
or 332 has a size of 1080 .mu.m.times.360 .mu.m. Referring to FIG.
7, a sustain electrode Sa and a sustain electrode Sb are provided
on a front substrate of the opposed discharge PDP and corresponds
to the sub-cells 331 and 332 respectively. The adjacent sub-cells
331 and 332 are parallel and one ends thereof are coupled together
to receive a voltage pulse sent from an electrode line 322. Thus, a
driving circuit (not shown) in the opposed discharge PDP is adapted
to apply a sustaining pulse to each of a plurality of electrode
lines in a sustaining period of each sub-field. As such, a phase of
the sustaining pulse on the sustain electrode Sa (or Sb)
corresponding to either sub-cell 331 (or 332) is adapted to have a
phase difference of 180 degrees relative to that of the sustaining
pulse on the sustain electrode Sa (or Sb) corresponding to the
other adjacent sub-cell 331 (or 332) such that the sub-cells 331
and 332 of adjacent pixels may discharge in opposite
directions.
[0031] Referring to FIG. 8, a driving scheme is created by the
driving circuit of the opposed discharge PDP for showing each
sub-field in the first preferred embodiment. The driving scheme
comprises three driving periods (i.e., a first addressing period, a
second sustaining period, and a third erasing period). Referring to
FIG. 9, the driving circuit applies a negative voltage pulse to
each of the sustain electrodes Sa and Sb in the addressing period.
At the same time, the driving circuit applies a positive data pulse
to the address electrode "A" based on an image to be displayed.
Next, the driving circuit applies a sustaining pulse to each of a
plurality of electrode lines 322 of the opposed discharge PDP (see
FIG. 7). As such, a phase of the sustaining pulse on the n.sup.th-a
sustain electrode Sa (or n.sup.th-b sustain electrode Sb) has a
phase difference of 1/2 period (i.e., T/2) relative to that of the
sustaining pulse on the n+1.sup.th-a sustain electrode Sa (or
n+1.sup.th-b sustain electrode Sb). That is, waveform of voltage
pulse of the sub-cell 331 corresponding to odd number pixel is
delayed T/2 relative to that of the sub-cell 332 corresponding to
even number pixel in a sustaining period. As a result, discharge
direction of the sub-cell 331 corresponding to odd number pixel is
opposite to that of the sub-cell 332 corresponding to even number
pixel in order to effectively eliminate noise caused by vibration
of the PDP in discharge as shown in FIG. 9. Finally, the driving
circuit applies an erasing pulse to each of the plurality of
sustain electrodes Sa and Sb of the PDP in the erasing period. As
such, wall charge of each discharge cell is eliminated. In the
embodiment waveform of a sub-cell 331 corresponding to the odd
number pixel is delayed T/2 relative to that of a sub-cell 332
corresponding to the even number pixel in the sustaining period.
Such driving method has advantages of without modifying driving
scheme in reset period and addressing period.
[0032] Referring to the above first preferred embodiment again,
discharge direction (i.e., vibration direction) of the sub-cell 331
corresponding to the odd number pixel is opposite to that of the
sub-cell 332 corresponding to the even number pixel. Thus, noise
generated by the sub-cell 331 is opposite to that generated by the
sub-cell 331 and they are cancelled each other due to opposite
vibration directions. As an end, noise generated by vibration of
the PDP in discharge is substantially eliminated. Moreover, a
reduction of peak current and electromagnetic interference is made
possible. In addition, area coated with phosphor is significantly
increased because the discharge cell 33 is divided into two
sub-cells 331 and 332. Further, distance between discharge center
and phosphor on either upper end (or lower end) of the original
discharge cell 33 is greatly decreased. As a result, UV is
sufficiently employed, light emitting efficiency of phosphor is
greatly improved, both light emitting efficiency and brightness of
the opposed discharge PDP are greatly increased, and thus image
with high quality is shown.
[0033] Referring to FIG. 10, a second preferred embodiment of the
invention is illustrated with respect to an opposed discharge PDP.
A transverse barrier rib 423 is provided on a center of any
elongate discharge cell 43 in any pixel so as to divide the
discharge cell 43 into two sub-cells 431 and 432. That is, n.sup.th
row discharge cell is divided into n.sup.th-a row sub-cell 431 and
n.sup.th-b row sub-cell 432. A sustain electrode Sa and a sustain
electrode Sb are provided on a front substrate of the opposed
discharge PDP and corresponds to the sub-cells 431 and 432
respectively. Thus, a driving circuit (not shown) in the opposed
discharge PDP is adapted to apply a sustaining pulse to each of a
plurality of sustain electrodes Sa and Sb in a sustaining period of
each sub-field. As such, a phase of the sustaining pulse on the
sustain electrode Sa corresponding to the sub-cell 431 is adapted
to have a phase difference of 180 degrees relative to that of the
sustaining pulse on the sustain electrode Sb corresponding to the
adjacent sub-cell 432 such that the sub-cells 431 and 432 of the
discharge cell 43 in the same pixel may discharge in opposite
directions.
[0034] Referring to FIGS. 11 and 12, in the second preferred
embodiment, the driving circuit applies a negative voltage pulse to
each of the sustain electrodes Sa and Sb of the PDP for showing
each sub-field in the addressing period. At the same time, the
driving circuit applies a positive data pulse to the address
electrode "A" based on an image to be displayed. Next, the driving
circuit applies a sustaining pulse to each of a plurality of
sustain electrodes Sa and Sb of the opposed discharge PDP. As such,
a waveform of the sustaining pulse on the nth-a sustain electrode
Sa is delayed T/2 relative to that of the sustaining pulse on the
adjacent n.sup.th-b sustain electrode Sb. Also, a waveform of the
sustaining pulse on the n+1.sup.th-a sustain electrode Sa is
delayed T/2 relative to that of the sustaining pulse on the
adjacent n+1.sup.th-b sustain electrode Sb and so on. As a result,
discharge direction of the sub-cell 431 of the discharge cell 43 is
opposite to that of the sub-cell 432 thereof in the same pixel in
order to effectively eliminate noise caused by vibration of the PDP
in discharge as shown in FIG. 12.
[0035] Referring to FIGS. 13 and 14, a third preferred embodiment
of the invention is illustrated with respect to the same
configuration of the sustain electrodes shown in FIG. 10. The
driving circuit applies a negative voltage pulse to each of the
sustain electrodes Sa and Sb of the PDP for showing each sub-field
in the addressing period. At the same time, the driving circuit
applies a positive data pulse to the address electrode "A" based on
an image to be displayed. Next, the driving circuit applies a
sustaining pulse to each of a plurality of spaced sustain
electrodes Sa and Sb of the opposed discharge PDP. As such, a
waveform of the sustaining pulse on the n.sup.th-a sustain
electrode Sa is delayed T/2 relative to that of the sustaining
pulse on the adjacent n+1.sup.th-b sustain electrode Sa. No voltage
is applied to the n.sup.th-b sustain electrode Sb and the
n+1.sup.th-b sustain electrode Sb in order to delay a waveform of
the voltage pulse on the sustain electrode Sa T/2 relative to that
of the voltage pulse on the spaced sustain electrode Sb in
sustaining period. As a result, discharge direction of the sub-cell
531 is opposite to that of the spaced sub-cell 532 (see FIG.
14).
[0036] Referring to FIG. 14 in conjunction with the waveform of
FIG. 13 an interlace based discharge method of the third preferred
embodiment is illustrated. For showing even number fields, both the
n.sup.th-b and the n+1.sup.th-b sustain electrodes Sb are
maintained at zero potential and a phase of the waveform of the
n.sup.th-a sustain electrode Sa has a phase difference of 180
degrees relative to that of the n+1.sup.th-a sustain electrode Sa.
Likewise, referring to FIG. 16 in conjunction with the waveform of
FIG. 15 for showing odd number fields, both the n.sup.th-a and the
n+1.sup.th-a sustain electrodes Sa are maintained at zero potential
and a phase of the waveform of the nth-b sustain electrode Sb has a
phase difference of 180 degrees relative to that of the
n+1.sup.th-b sustain electrode Sb. Thus, the n.sup.th-a sustain
electrode Sa is a sustain electrode adapted to drive independently
relative to the n.sup.th-b sustain electrode Sb and vice versa in
order to control waveforms of the n.sup.th-a sustain electrode Sa
and the n.sup.th-b sustain electrode Sb respectively. As an end,
brightness of the corresponding sub-cell 531 can be controlled.
Also, the n+1.sup.th-a sustain electrode Sa is a sustain electrode
adapted to drive independently relative to the n+1.sup.th-b sustain
electrode Sb and vice versa in order to control waveforms of the
n+1.sup.th-a sustain electrode Sa and the n+1.sup.th-b sustain
electrode Sb respectively. As an end, brightness of the
corresponding sub-cell 532 can be controlled. For example, in a
period of showing a specific sub-field waveform of voltage pulse
the n.sup.th-a sustain electrode Sa is maintained as the waveform
of voltage pulse in sustaining period and voltage of the n.sup.th-b
sustain electrode Sb is maintained as constant. As such, only
sub-cell 531 corresponding to the n.sup.th-a sustain electrode Sa
may discharge to emit light while sub-cell 532 corresponding to the
n.sup.th-b sustain electrode Sb may not discharge (i.e., no light
is emitted). Such independent brightness control with respect to
the sub-cell 531 (or the sub-cell 532) corresponding to the
n.sup.th-a sustain electrode Sa and the n.sup.th-b sustain
electrode Sb has the following advantages:
[0037] (i) A minimum brightness can be obtained. The sub-cell 531
corresponding to the n.sup.th-a sustain electrode Sa may discharge
to emit light while the sub-cell 532 corresponding to the
n.sup.th-b sustain electrode Sb is dark due to no light emission.
Thus, brightness of the opposed discharge PDP is about half of that
when both the sub-cell 531 corresponding to the n.sup.th-a sustain
electrode Sa and the sub-cell 532 corresponding to the n.sup.th-b
sustain electrode Sb are lit. As a result, a minimum brightness is
obtained for rendering fine image in low gray-scales of the opposed
discharge PDP.
[0038] (ii) Brightness in discharge can be finely adjusted. Either
the sub-cell 531 corresponding to the nth-a sustain electrode Sa or
the sub-cell 532 corresponding to the n.sup.th-b sustain electrode
Sb can be prohibited from discharging when brightness in discharge
is higher than an ideal value. As a result, brightness of the
opposed discharge PDP is decreased and thus the purpose of
adjusting brightness of each gray-scale is obtained.
[0039] While the invention herein disclosed has been described by
means of specific embodiments, numerous modifications and
variations could be made thereto by those skilled in the art
without departing from the scope and spirit of the invention set
forth in the claims.
* * * * *